Start with the numbers: Seven candidates. Eight months of competition. Thirteen debates. Thirteen million dollars in mostly vicious and anonymous TV attack ads. A final day with 23 events in a state of 3 million people. The simple goal: persuade some small fraction, maybe 5% of Iowa adults, or 120,000 souls, to give up their Tuesday night, sit in a room for an hour and help determine the fate of a fearful nation. Get just a fraction of that fraction, maybe 30,000, to support you, and you carry the day.

One could say late Monday night that the Republican presidential primary campaign in Iowa was unfolding as expected as it entered its final hours. But that would insult the process, which is so absurd, so dependent on chance, theater and the whim of the indecisive as to defy expectation. Who would have guessed that in the final days not a single candidate would have launched a sustained attack on the yearlong front runner, Mitt Romney, who is disliked by an alarming portion of his own party? Who could have foreseen that a 76-year-old obstetrician, Ron Paul, would be drawing the youngest, rowdiest crowds? Who would have predicted that the one candidate who never budged in the polls, Rick Santorum, would be surging at the wire? That the final pre-caucus polling would show a total pileup at the front of the pack?

It’s O.K. to admit that none of it makes sense. The world’s richest, most advanced democracy has randomly endowed a few thousand residents of a state known mainly for corn, hogs and gas stations called Kum & Go with the responsibility of screening its prospective leaders. A thousand or so journalists fly in from New York City, Chicago, Washington and Los Angeles to keep score and promote the proceedings. The crowds turn out at dawn in the frigid cold, with homemade signs and questions about Iran and immigration. Everyone keeps a straight face. They put up with the television spots. They get used to the lawn signs. Because that’s how it is. “Iowa is the big sifter,” explained Jess Paul, a retired Republican in a town called Clinton, who last week turned out to see Romney speak, even though like most caucusgoers, he had not yet decided on a candidate. “It should take out the bigger hunks of chaff.”

As a candidate certain to sift through, Romney spent his final days recounting the lyrics of patriotic poems and songs, and then singing his own odes to the horribleness of the sitting President. It was as rational a response as any. He compared Barack Obama to Marie Antoinette, accused him of not understanding his country and declared the election a battle between opportunity and entitlement, between a society of ambition and one of envy. Something had changed in Romney from four years earlier, the last time he was in the state, when he lost to Mike Huckabee like Goliath lost to David: too big, too slow and unprepared for the agility of his foe. The stress did not show so much on Romney’s face. He no longer tried so hard to impress. He knew what he was doing, on a day that brought him to Davenport, Dubuque, Marion, Cedar Rapids and Clive. By most accounts, he was winning.

Romney’s closest contender in the polls, the good doctor Representative Paul, a Texas septuagenarian with a runner’s physique, operated in a different sphere, less worried about Obama or victory than the crop of libertarian followers he was sowing in the heartland. He sold himself literally as “the One,” a savior promising a new era of gold coins, world peace and legal weed. “It’s the youth that likes him,” said Daniel Solon, 19, a student at Hawkeye Community College. “They’re the future. The old ways have shown that they’re faltering. And the young people will grab that torch for liberty and carry it forward.” At his rallies, the crowds chanted “Ron! Paul!” like a rock audience demanding an encore. “Preach it,” another enthusiast demanded of the candidate. “Tomorrow is a very important day. Small numbers but very big message,” the candidate told his crowd. “You carry a lot of weight in this state. Send a message on which way we’re going.”

Paul’s campaign manager and son-in-law, Jesse Benton, maintained that the campaign had a clear plan to win the nomination by building momentum through Florida. It was the sort of professional optimism that campaign operatives are paid to deliver, even if it was unhinged from reality. To Paul’s credit, he did not seem to believe it himself. Asked in an interview with ABC News if he saw himself in the Oval Office, Paul responded plainly, “Not really, but I think it’s a possibility.” A “slim” possibility, he continued, which was probably too generous.

The next in the polling pecking order, former Pennsylvania Senator Rick Santorum, spent his day touring five towns in central Iowa. In recent days, his rise had attracted the first notice of his rivals. Paul called him “very liberal.” Romney dinged him as a “Washington insider.” And Texas Governor Rick Perry accused him of being a “serial earmarker.” But such attacks were a sign of Santorum’s strength, not weakness, especially since it brought the press out to places like Urbandale and forced Iowa’s social-conservative throng into yet another reconsideration of their vote, likely in his direction.

To raise the stakes, and deepen the oddity of the exercise, Santorum introduced a special guest at his events, Jim Bob Duggar, the father of 19 children by his wife and the star of a basic-cable show documenting their life. Duggar, moving seamlessly from one reality show into another, told the crowds that Santorum was imperfect but that every candidate is “unless it’s Jesus Christ.” This passed, it was agreed, as a perfectly effective message, given the circumstances.

The other candidates on the undercard, former House Speaker Newt Gingrich, Minnesota Representative Michele Bachmann and Perry, did their best to keep their heads high, even though many of the caucusgoers who once supported them in the polls had already bolted from the altar for another suitor. If there was chaff to be weeded out, it was this bottom group that feared the sieve the most. To project confidence, Perry released a schedule of planned events later this week in South Carolina, where Romney has a history of struggle. Gingrich projected into New Hampshire, where he promised to do a better job of attacking Romney. “I don’t think I am going to win Iowa,” he said, only a few weeks after predicting that the polls would hold and he would win the whole thing. Bachmann trundled on with barely a skeleton of a campaign remaining. Once the darling of the state’s Republican activists, Bachmann’s most pressing task after Tuesday’s caucuses will almost certainly have more to do with filing for re-election in Minnesota than taking on Obama in Ohio. Meanwhile, Jon Huntsman, the seventh candidate, lay in wait in New Hampshire with the hope that next week’s winnowing would be a bit more kind to the underdogs.

Amid all the din and long-distance driving, one thing was certain: by Wednesday, it would be over. The circus tents would fold and the performers would retool their acts for new audiences in climates less concerned with corn and soybean. That’s the way it goes in America. That’s the way the most powerful nation picks its most powerful leader. Don’t set aside the silliness. Don’t ignore the details. Sure, it doesn’t make sense. No one would design a process like this, least of all the Founding Fathers, who are so in vogue at the moment. But there remains a wonder to it all. And now we must wait to see what happens.